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Fosfomycin

Prescription
Phosphonic Acid Antibiotic
Last reviewed 21 Apr 2026 · PetCare.AI Editorial Team
Species
Dog, Cat
Brands
1 available
Formulations
2

Mechanism of action

Inhibits the first step of bacterial cell wall synthesis by blocking MurA (UDP-N-acetylglucosamine enolpyruvyl transferase), which catalyzes peptidoglycan precursor formation. Unique mechanism — no cross-resistance with any other antibiotic class. Active against MDR organisms.

At a glance

Class
Phosphonic Acid Antibiotic
Schedule
Prescription
Storage
Store at room temperature below 30°C

Dosing

🐕

Dog

Reserved for multidrug-resistant UTIs (ESBL-producing E
Dose
40–80 mg/kg
Route
PO, IV
Frequency
q8–12h
🐈

Cat

Used for MDR UTIs in cats
Dose
30–50 mg/kg
Route
PO
Frequency
q12h
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

Formulations

💊

Other — 2

Strength
Strength

Storage

Store at room temperature below 30°C

Safety

Monitoring parameters

Urine culture pre- and post-treatmentClinical responseRenal function
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

Interactions

No documented interactions.

Brands

Other markets

Monurol

FAQs

Frequently asked questions

What is Fosfomycin?
Fosfomycin is a phosphonic acid antibiotic used in pets. Inhibits the first step of bacterial cell wall synthesis by blocking MurA (UDP-N-acetylglucosamine enolpyruvyl transferase), which catalyzes peptidoglycan precursor formation. Unique mechanism — no cross-resistance with any other antibiotic class. Active against MDR organisms.
What is Fosfomycin used for in pets?
Fosfomycin is used in veterinary medicine for: Reserved for multidrug-resistant UTIs (ESBL-producing E; Used for MDR UTIs in cats.
What is the Fosfomycin dose for dogs?
For dogs, Fosfomycin is typically dosed as follows — Reserved for multidrug-resistant UTIs (ESBL-producing E: 40–80 mg/kg PO/IV q8–12h. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
What is the Fosfomycin dose for cats?
For cats, Fosfomycin is typically dosed as follows — Used for MDR UTIs in cats: 30–50 mg/kg PO q12h. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
Does Fosfomycin need a prescription?
Yes. Fosfomycin is a prescription medication and should only be administered under veterinary supervision.
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

References

References

The PetCare.AI drug reference is built from 13 authoritative sources cited across 580 drug monographs.

Textbooks & handbooks — 5

  • Plumb's Veterinary Drug Handbook
  • Withrow & MacEwen's Small Animal Clinical Oncology
  • Merck Veterinary Manual
  • NRC Nutrient Requirements of Dogs and Cats
  • Veterinary Pharmacology and Therapeutics (Riviere & Papich)

Clinical guidelines & consensus — 4

  • ASPCA Animal Poison Control Center Guidelines
  • AAHA Diabetes Management Guidelines
  • ASPCA Poison Control Guidelines
  • RECOVER CPR Guidelines

Journals & peer-reviewed studies — 2

  • EPIC Study (J Vet Intern Med 2016)
  • JVIM FAT CAT Study

Regulatory & approvals — 1

  • CDSCO Veterinary Drug Approval Registry (1969–2026)

Databases — 1

  • Washington State University VCPL MDR1 Database
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